Process of flotation for sylvinite ores



in the mineral sylvinite byflotation.

Patented Mar. 3, 19.42

2,275,138 v PROCESS OF FOR SYLVINI'IE Fritz E. Fuchs, Houston, Tex, assignor Wilmington, Del, a corpora- Corporation, Ltd., tion of Delaware No Drawing.

12 Claims.

This invention relates to "improvementsin the separation of potassium chloride from sodium chloride and associated impurities as they occur It relates more particularly to the use, as a flotation reagent or collector, in such a procem, of carboxylic acids derived from oxidized petroleum, and more particularly to the use of the neutralized fraction in which are concentrated the acids having from 7.to 11 carbon atoms.

The mineral sylvinite is a valuable source of potash. It consists principally of a mixture of potassium and sodium chloride, with small percentages of iron and such foreign matter as clay in varying, usually small, amounts. One method of removing the potassium chloride from the sodium chloride and associated impurities is by flotation, the raw ore, which. contains around 40% potassium chloride and 60% sodium chloride, with traces of iron, clay, etc., being ground and then floated in a rougher-middlecleaner cell installation, using a saturated brine as a carrier and medium. In one process being commercially used, the sodium chloride, together with the slime is removed in the froth, while the potassium chloride, along with much of the iron, is concentrated in the underflowl from the cleaner cell, whence it goes to a centrifuge for drying and further treatment. The purity of the recovered potassium chloride usually runs around 97-98% the plant, and a purity of less than 95% is regarded as inadequate separation. The brine, after'removal of the sodium chloride and potassium chloride, is recirculated to minimize the amount of the potassium and sodium chlorides which are dissolved in the carrier fluid.

In accordance with the present invention,

potassium chloride is separated from the sodium' chloride, clay, etc., with the use brine as a medium or carrier in a closed cycle, following substantially the same procedure now used, and with the use of a reagent consisting of carboxylic acids derived from petroleum by an oxidation process and containing 7 to 11 carbon atoms in the carbon-linked chain, or a suit ably derived fraction in which these acids are concentrated or predominant. Advantageously, a fraction consisting primarily of the C1 to C9 acids, with minor amounts of higher and lower acids and associated impurities, is used. Such acids may be used as such, or may be used in the form of sodium, potassium or other salts, although the use of the alkali metal salts is adof a saturated to Peh'ollte Application February 17, 194., Serial No. 319,468

vantageous. Along with such acids as the collector or flotation reagent, it is advantageous to use a relatively small amount of a lead compoundand a conditioning agent, such as the commonly used cresylic acid, as the separation of the potassium chloride from the sodium chloride is greatly facilitated by the addition of such materials along with the flotation reagent.

The amount of flotation reagent which is required is relative small, less than one pound of the reagent per ton of ore giving highly satisfactory results; but the amount will vary depending upon the coarseness of the grind of the ore, the purity desired in the separated potassium chloride, etc.

The use of these reagents in eration has a number of important advantages. It permits the coarser grinding of the crude .ore while ob eifective separation, thus eifecting a substantial decrease in grinding and similar costs. The reagent may, if used in sumcient amount, be so eflective in the separation of relatively coarse feed as to the flotation apparatus an ore much coarser than the feed now used and yet enable the production of a highly purified potassium chloride.

When the new reagents are used, the amount of water which must be added along with the reagent is substantially less than that required to be added with the reagents now commonly used, both because the new reagents are substantially more soluble in water and because they give eflective separation in much smaller amounts than is required with used. This is an important advantage, because any addition of water results in the dissolving of more of the ore in the brine, and substantially increases either the operating losses or operating expenses, and because of the tact that water must be hauled, at considerable expense, to the mills in which sylvinite is processed.

The reagents used in accordance with the invention may be prepared by oxidizing such petroieum distillates as kerosene, and separating from the resulting products a fraction in which the carboxylic acid having from 7 to ll earls-on atoms are concentrated. For example, a Pennsylvania distillate of 45 A. P. I. gravity or kerosene may he oxidized by blowing with air, or oxygen, or oxygen enriched air, at temperatures up to C. and relatively high pressures with the use of a small amount of an oxidation catalyst such as manganese oleate, distilling the resulting mixture to remove some of the hydroxy and ketone acids, alcohols, poly-alcohols, ketones, ketone-alcohols, etc.,

this notation onthe reagents now neutralizing the important advantages over remaining product, dissolving it in water to-remove unsaponifiable matter and then regenerating the acids by the addition '0! mineral acids. After washing the resulting prodnet with water, a mixture of straight and branched chain monocarboxylic acids, usually beginning with the C5 acids, and containing greater or lesser proportions of associated impurities, is obtained. The resulting acidic mixture is fractionated, and the fraction containing the acids having from 7 to 11 carbon atoms is separated and used as the reagent in accordance with the invention. This fraction will, of course, contain a certain amount of impurities oi the most diverse kind, including appreciable amounts of acids having more than 11 or less than 7 carbon atoms, lactones, hydroxy acids, esters, etc., and the effectiveness of the reagent may be considerably improved by further purification to obtain the acids having from 7 to 11 carbon atoms in a more pure form. but such further purification is not essential. These carboxvlc acids include both straight and branched chain compounds, and form a complex mixture, which contains a number of constituents in additionto the carboxylic acids, e. g., lactones, aco

hols, etc., but the exact nature of the m xture is not known. They diflfer from the straight-chain fatty acidshaving from 7 to 11 carbon atoms, as these straight-chain fatty acids are solid. at icebox temperature, while the mixture of acids used as the reagent in accordance with this invention is liquid'even at such temperature.

While, as pointed out above, ture resultingtrom the production 0! a fraction consisting predominantly'o! carboxylic acids having '7, to 11 carbon atoms forms a highly effective reagent, particularly when completely or parthe complex mixfreed from accompanying brine.

tially neutralized, as with caustic soda, a corresponding fraction consisting predominantly of carboxylic acids having '7 to 9 carbon atoms, together with associated impurities and lesser quantities of higher and lower acids gives substantially forms reagents having those formed from the better results, and hence less closely cut fraction.

The acid mixture may be used as such, or may The alkali metal salts appear The invention will be further illustrated by the following specific example, but it, is not limited thereto.

Exampla-Raw sylvinite ore is crushed, wet ground in a ball mill, screened and then ifedas a 30% pulp to flotation cells arranged as rougher, middle; and cleaner cells. The reagent, prepared as above, in the form of the sodium salt, is added, in aqueous solution, to each of the cells, a small amount being added to the rougher cell a larger proportion to the' middle cell, and a small amount, slightly more than the amount in the rougher cell, being added to the cleaner cell. Usually, considerably less than a pound of reagent per ton of ore, for example, 0.6 pound of reagent per ton of one, gives highly satisfactory results. A conditioning agent, such as'cresylic acid, is advantinuously or periodically. for example, three times y a day. to adjust the lead content of the brine to the 2.0 grams per gallon. The froth from the middle and cleaner cells is recycled through the rougher cell, the froth from which goes back to the refinery. The underflow from the rougher cell goes to the middle cell and the underflow from the middle cell to the cleaner cell. The underfiow from the ceaner cell goes to a centrifuge, where the purified potassium chloride crystals are recycled through the ball mill.

1 claim: 1.,The process of concentrating potassium chloride from a sylvinite ore by a flotation process which comprises using as a flotation reagent a material of the class consisting of acidic fractions of petroleum oxidation carboxylic acids in which acids having seven to eleven carbon atoms are concentratedand'products resulting from at least the partial neutralization thereof.

2. The process of concentrating potassium chloride from a sylvinite ore by a flotation process which comprises using as a flotation reagent a material of the class consisting of acidic fractions of petroleum oxidation carboxylic acids in which acids having seven to ninecarbon atoms are concentrated and products resulting from at least the partial neutralization thereof,

3. The process as in claim 1, in which the flotation reagent is the specified acidic fraction with at least apart of the carboxylic acids converted to their alkali metal salts.

4. The process as in claim 1, in which the flotation reagent is the specified acidic fraction with at least a part of the carboxylic acids converted to their sodium salts.

5. The process as in claim 2, in which the flotation reagent is the specified acidic fraction with at least apart of the carboxylic acids converted to their sodium salts.

6. The process of concentrating potassium chloride from a sylvinite ore by a flotation process which comprises using as a flotation reagent a neutralized acidic fraction 01- petroleum oxidation carboxylic acids in which acids having from seven to eleven carbon atoms are concentrated.

'7. The process of concentrating potassium chloride from a sylvinite ore by a flotation process which comprises using as a flotation reagent a neutralized acidic traction of petroleum oxidation carboxylic acids in which acids having from seven to nine carbon atoms are concentrated.

8. The process of concentrating potassium chloride from a sylvinite. ore by a flotation process which comprises using as a flotation reagent the alkali metal salts of petroleum oxidation carboxylic acids having seven to eleven carbon atoms.

9. The process of concentrating potassium chloride from a sylvinite ore by a flotation rocess which comprises using as a flotation reagent the alkali metal salts of petroleum oxidation carboxylic acids having sevento nine carbon atoms.

10. The process of concentrating potassium chloride from a sylvinite ore by a flotation process which comprises using as a flotation reagent a mixture of petroleum oxidation craboxylic acids having sevento eleven carbon atoms.

11. The process as in claim 1, in which, in addition to the flotation reagent, cresylic acid is used as a conditioning agent.

12. The process as in claim 1, in which a lead salt is used in addition to the flotation reagent.

FRITZ E. FUCHS.

The brine is 

